Several methods for producing iron methacrylate have been proposed.
For example, a method has been proposed, in which methacrylic acid, an alkaline metal and an iron salt such as iron nitrate are mixed in a solvent such as water, and iron methacrylate is produced by salt exchange (Patent Literature 1). Since this method has a difficulty in securely completing salt exchange, iron methacrylate is difficult to obtain in a high yield of 90% or higher. The method has further problems such as a reduction in purity due to contamination of iron methacrylate with impurities derived from nitric acid, and a rise in the cost because of necessity of filtration and drying processes. In the case where a hydroxyalkyl methacrylate is produced by using the prepared iron methacrylate as a catalyst, there are concern about problems, such as by-production of impurities, coloration and the like derived from nitric acid contained in the catalyst raw material.
Other methods include a method in which a metallic iron is dissolved in methacrylic acid (Patent Literatures 2 and 3). Since iron methacrylate prepared by this method is obtained as a solution of methacrylic acid containing iron methacrylate, the solution is suitable because the solution can be used as it is for production of a hydroxyalkyl methacrylate by using the iron methacrylate as a catalyst and the methacrylic acid as a raw material. That is, since filtration and drying processes and the like are not needed, the production cost can be reduced. A high-quality hydroxyalkyl methacrylate which contains no impurities derived from halogens, and exhibits little coloration can be produced.